Edit: Just want to make it clear that I'm referring to the use of walls to defend against an attacking army, rather than against infiltrators/civilians etc. So something like the Berlin wall doesn't count.

Gunpowder didn't make walls obsolete, per se, what gunpowder did was make tall thin walls (ie. castle walls) relatively obsolete. However, if you look at walls of Quebec you can see that walls could still be used to protect a city as late as the late 1600's.

Quebec, Saint Augustine (Florida), and Charleston (South Carolina) all had stone walls designed to defend against European armies. I don't know if they were ever actually used as a fighting platform, and I'm pretty sure Charleston's never were.

I'm 90% sure it was. All of the sources I'm finding while unsuccessfully looking for a map of the fortifications for you seem to indicate that Castillo de San Marcos was just one part of the fortification. But I used to be a historical tour guide in Charleston, and part of the tour was mentioning the city as one of three walled cities in continental North America, which left out other cities like New York that had a fort and a minor wall defending the city. And one of our strengths was, unlike the carriage tour drivers, we didn't just make stuff up.

I'm not saying that he was a liar, exactly. They don't just fabricate stories that never really happened. I'm saying that, if there's a hole in a brick wall he doesn't know the cause of, it's always from a civil war cannonball.

Charleston is actually one of the only US cities that require its tour guides to pass a test and get a tour guide license; I think New York might be the only other city that does that. That having been said, confusing Fort Sumter with Fort Moultrie is inexcusable, especially since the most interesting parts of their histories are from two different wars.

Fort Moultrie actually repelled one of the first full-scale British attempts to suppress the colonial uprising. The British bombarded the fort, but since its walls were made of Palmetto logs which are soft and spongy, the cannonballs just bounced off instead of causing real damage. The South Carolina state flag comes from that battle: they added a palmetto tree to a revolutionary flag designed by the commander of the fort.

Sorry, I know nobody really asked about that, but I said it 12 times a day for a few months, so if I don't say it every once in awhile I get cramps.

Battle of Hue is another case where walls held up in modern warfare. The walls to the imperial city is about 1 meter in thickness, 3 meters high, surrounded by the perfume river in the front and moat on the remaining 3 sides. (The moats were drained when I was there in 2010, not sure if were back in the '68.) The initial frontal assault by the marines was easily repelled. The later assault from the rear took days to make little headway. It wasn't really until South Vietnam gave the US permission to use air force on the imperial city that the palace was retaken.

I do have very little knowledge on the Vietnam War, but wasn't the main reason the walls weren't destroyed because the Americans hesitated to do so out of respect to the ancient buildings? AFAIK the fear of a shitstorm like the criticism after Monte Cassino played a major role in the plannings of the battle.

wasn't the main reason the walls weren't destroyed because the Americans hesitated to do so out of respect to the ancient buildings?

Yep, Hue city in general is highly symbolic to the Vietnamese people. But I doubt the wall themselves are that important. It was mainly the structures inside the imperial palace that carries cultural significance. Most of these buildings were made out of wood which is why napalm was not used until near the end of the battle. Those buildings still ended up being destroyed. If you tour the palace today, less than 1/3 of the original building remains standing. The rest are earth mounts and walls. Some of the walls still carry the original bullet marks.

It depends on what you consider "a wall". Technically every time an infantryman or sniper makes use of an existing building, he's using the walls as support. What else holds up the ceiling?

While that seems semantic, consider the siege of Stalingrad in WWII, where every building was made into a fort by booby trapping, positioning snipers, ect. Walls are good defensive structures in every war. Gunpowder made them obsolete as much as they did water bottles.

But concerning Medieval Walls, where the wall is one structure surrounding a city, that morphed into the Star fort. You have to check them out, they're awesome. Go on Wiki at least, I'll wait here.

If you look at a european city map from the 16th/17th century, almost all with money to build them have these jagged outlines. Besides being really cool shapes, they were super effective, and absolutely have walls.

The walls are now low and thick with earth behind them. On top sit the the cannons with lines of cross-coverage, to prevent infantry from being able to find cover. If your first reaction is: "well, blow up the artillery then" Yes, that is what they tried and tried, but it took a long time. Sieges became artillery battles, if not about the always present hunger games.

But the defenders still had advantages. Offensive cannons can maneuver less in the mud. The men around them have less cover. Sieges in the early modern era actually took longer thanks to gunpowder.

The defenders don't have to make new land measurements concerning distance and elevation for with every city. And so it becomes a game of plotting trajectories, which is why you learn these things in physics. By the way, FYI Napoleon's first job in the army was with the cannoneers brigade. He had studied at the military academy in Paris, and had quite the knack for calculus.

In general, the cost of taking these things was huge. Like, "I have to draft the population of France" huge.

When the cities and artillery ranges grew larger, they stopped using one big one of these ("a" wall), and used a ring of overlapping forts around the city. Still, for good measure, there was sometimes one large wall around all of it. In the case of Paris, the Thiers wall

Those fortifications only became obsolete very late, when shells became explosive enough to leave craters behind. So that's 19th century artillery, and the first real use of them was in 1871 at Paris.

That's my vote for the last time the forts held out, because it wasn't until a year into the siege, three days after Bismarck ordered no-hold-barred bombardment, that Paris surrendered rather than see itself leveled.

And then after a largely peaceful period, along comes WWI, which is story in itself, but suffice it to say, artillery accounted for 70% of military casualties. It's defense is less dependent on stone walls, and more on machine guns, barbed wire, ect. To consider a trench a makeshift wall is probably far-fetched, but you get my point.

Afterwards, most cities demolish their walls and forts to make room for housing. That is also part of the reason why the German conquest of Western Europe was comparatively fast, once the fronts were gone, the cities were largely defenseless.

And so we circle round to Stalingrad, and the modern era, where both every house can be a fort, and every city is a within range of being blown up.

No, but gunpowder forced them to change the design of the fortifications. What went away first were corners, because they were easy to shatter with cannons. So that's why nearly all castles today have round towers. Then, in the 15th century, there evolved star forts and bastions, which were more difficult to conquer with cannons. Fortifications were even used in the Naopleonic wars and they became obsolete only by the mid-19th century.

Badajoz, in Spain, is the site of a Moorish citadel built from the 8th to 11th century, it was the scene of three sieges by the French when occupied by the Spanish in the early 19th Century, and it was only on the third time when the Spanish commander was bribed by Marshal Soult that the fortress was taken. When occupied by the French it also survived a brace of sieges by the Spanish and the British/Portuguese before a larger Anglo-Portuguese army took it after suffering a huge amount of casualties due to the French fortifying the cannon-made breaches in the walls, and it was only once another part of the castle was scaled with ladders that the Allies managed to put an end to the conflict (though the sacking of Badajoz which occurred afterward was horrific).

As others have said, cannons didn't make them obsolete, but it drastically reduced their usefulness.

A long time ago I read that the Chinese made use of city walls (every Chinese town had a wall back then) against the Japanese in the Sino-Japanese war of the 1930s. I no longer remember where I read that, but this source seems to confirm it.

Battle of Nanjing was quite interesting. The city gates was built during Ming dynasty. Each brick has the name of the person who made it. So the quality of construction is extremely high. When the Japanese tried to breach the main gate (zhong hua men), the cannon would bounce off the walls. The main gate itself is a series of 4 gates with traps and tunnels to surprise the intruders. Eventually the Japanese gave up on attacking the main gate and blew 2 holes on the walls immediately next to it and marched in. What followed is the Rape of Nanjing where 30 million 300,000 people lost their lives.

There is a place on the French/Italian border (I think near Sestriere, but I can't find it on Google Maps) where there is a wall fort which spans an valley, about 3/4 of a mile in length. It has a 30' ditch in front of it, and the fort itself has 2-3 floors above ground, and was equipped with heavy guns which were pivoted to rotate through about 90 degrees, firing through embrasures. At least one gun is left in place, which from its appearance appears to date from the early 19C.

No. You would protect your walls with a glacis so that cannon couldn't hit them directly. A glacis is really just an earthen ramp in front of your wall. It served to deflect and absorb the force from cannon.

Gunpowder certainly made taller walls much more difficult to defend and keep standing.

well that depends on what you mean effectively trenches served the same purpose as walls and the fences they put around military bases are just a wall you can look through. The Alamo is a good example of a later age attempt at the wall up and defend method which may have worked if the balance of forces was not so one sided.

personally i believe walls lost there effectiveness as protecting the population as a whole became more important to the country then protecting its leaders. Honestly Castles and walls were only really built to protect the leaders of the countries there was never enough space to fit your whole population inside the gates and many people were just left on your own. as the rights of citizens in countries has increased the ability of its leaders to use them as a meat shield has dropped sharply....